1. Field of the Invention
The present invention relates to a photoelectric conversion apparatus.
2. Description of the Related Art
CCD and CMOS photoelectric conversion apparatuses are used in a multiplicity of digital still cameras and digital camcorders. Particularly, the CMOS photoelectric conversion apparatuses are superior in power consumption and multi-functionality, and the application range is expanding in recent years.
Recently, miniaturization of pixels is demanded in the photoelectric conversion apparatuses, and chemical mechanical polishing (CMP processing) is performed as a miniaturization process in the formation of a plug. FIG. 1 of Japanese Patent Application Laid-Open No. 2008-218755 describes a configuration of a contact when the CMP processing is executed to form a plug. Japanese Patent Application Laid-Open No. 2008-218755 tackles a problem that there is a difference in the dark current of an optical black pixel region and an effective pixel region, and barrier metal layers are formed by layers including a titanium nitride layer and a titanium layer.
Mitsuru Okigawa, “Low-Damage Plasma Process for Solid-State Imaging Element”, The Institute of Image Information and Television Engineers Technical Report, Vol. 28, No. 23, pp. 19 to 22 describes that an ultraviolet ray of 250 to 350 nm generated in a plasma process, such as etching and CVD, increases an interface state between silicon and a silicon oxide film and causes a dark current.
The present inventors have found out that the difference in the dark current of the optical black pixel region and the effective pixel region is influenced not only by a hydrogen-terminated treatment but also by a damage caused by the ultraviolet ray of 250 to 350 nm in etching and plasma processing.
The present invention has been made in view of the foregoing problem, and an object of the present invention is to provide a photoelectric conversion apparatus and an imaging system capable of reducing a difference in the dark current of an optical black pixel region and an effective pixel region when a miniaturization process is executed.